While cigarette smoking is declining in the U.S., an emerging form of tobacco use, waterpipe tobacco smoking (WTS), is increasing. WTS is now nearly as common as cigarette use for college students, and it is also prevalent among high school and non-college adult populations. Because as many as 50% of WTS users do not smoke cigarettes, it affects many who would otherwise have been tobacco naive. This is of particular concern because a typical WTS session may deliver over 100 times the smoke volume of a single cigarette. Although clean indoor air policies and regulations have rapidly propagated throughout the U.S., more than 90% of these laws do not address WTS, possibly fueling increased WTS. Furthermore, the recently enacted FDA Family Smoking Prevention and Tobacco Control Act (FSPTCA, HR 1256) does not specifically include WTS in its stipulations. Therefore, we designed this project to generate in-depth information urgently needed to inform and clarify federal and state policy in this area. States often serve as laboratories for federal policy, and because states and municipalities directly regulate the businesses that sell tobacco, effective WTS policy will require combined state and federal authority. As a microcosm of the U.S.-both in terms of geopolitics and tobacco control policies-Pennsylvania is the ideal state to study these topics. Therefore, we designed a two-phase project which will enable us to provide detailed, evidence- based recommendations for future tobacco-control legislation that will take into account the complex dynamics of WTS and will allow us to proactively engage with policy leaders around WTS. First, we will comprehensively analyze all relevant extant tobacco policies of each of the 8 official Health Districts (HDs) sanctioned by PA. For each HD, we will simultaneously examine laws on the municipal and county level, including how they interact with state and federal policy. We will systematically assess how language within these texts applies to WTS regarding each of the primary ways tobacco is regulated, including use restrictions, youth access, price (e.g., taxation), flavorings, and labeling. Second, we will explore WTS and its associated legal issues with influential individuals who have been and/or may be in the future involved in tobacco-related legislation in Pennsylvania in the past, including (1) legislators and staff; (2) public health officials; and (3) advocacy group leaders. We will use structured templates for in-depth interviews to explore particular issues such as (1) knowledge, attitudes, and beliefs related to WTS; (2) clarification of intentions and realities of specific provisions and/or exemptions of prior legislation (3) perceived consequences of any legislation passed; and (4) interactions between municipal, state, and FSPTCA provisions. Synthesis of information from document analyses and in-depth interviews will directly inform optimal policy-making on multiple levels to reduce WTS.